Gas producer having ash removal plates with individual temperature sensing

ABSTRACT

There is provided an improved large diameter vertical gas producing apparatus which is characterized by a grate and ash removal system which facilitates production of gas from solid carbonaceous material in a large diameter furnace. The improved grate/ash removal system is characterized by a plurality of concentrically disposed tubular members having their proximal extremities extending into the lower region of said furnace. These tubular members are individually supported at different levels and guide the ash produced onto axially displaced concentric annular rings. Individually rotatable ash scrapers coact with each of said annular rings to guide the accumulated ash off of the annular ring for collection in a conventional ash cone. The rate at which the ash removal scrapers remove ash from the concentric annular rings is variable and may be in response to temperatures sensed near the grate and in the upper region of the tubular members to aid in maintaining across the large diameter control of burning.

United States Patent 1191 Hamilton 1 Nov. 12, 1974 [75] Inventor: George M. Hamilton, Marlton, NJ.

[73] Assignee: McDowell-Wellman Engineering Company, Cleveland, Ohio [22] Filed: Jan. 11, 1973 [21] Appl. No.: 322,738

[52] US. Cl 48/76, 23/277 R, 48/87,

48/203, 110/31 [51] Int. Cl. ClOj 3/52 [58] Field 01. Search 48/67, 68, 69, 76, 203,

[56] References Cited UNITED STATES PATENTS 1,590,142 6/1926 White et al. 48/76 1,837,226 12/1931 Loebell 48/203 2,185,077 12/1939 Galusha 48/76 3,454,382 7/1969 Hamilton 48/76 2,440,940 5/1948 Galusha 48/76 1,520,539 12/1924 Duckett 1 4 48/66 1,609,128 11/1926 Richardson 48/69 3,258,409 6/1966 Schenck et al. 48/203 X Korting 110/31 X Primary Examiner-S. Leon Bashore Assistant ExaminerAlfred DAndrea, Jr. Attorney, Agent, or FirmMcNenny, Farrington, Pearne & Gordon [57] ABSTRACT There is provided an improved large diameter vertical gas producing apparatus which is characterized by a grate and ash removal system which facilitates production of gas from solid carbonaceous material in a large diameter furnace. The improved grate/ash removal system is characterized by a plurality of concentrically disposed tubular members having their proximal extremities extending into the lower region of said furnace. These tubular members are individually supported at different levels and guide the ash produced onto axially displaced concentric annular rings. lndividually rotatable ash scrapers coact with each of said annular rings to guide the accumulated ash off of the annular ring for collection in a conventional ash cone. The rate at which the ash removal scrapers remove ash from the concentric annular rings is variable and may be in response to temperatures sensed near the grate and in the upper region of the tubular members to aid in maintaining across the large diameter control of burning.

6 Claims, 3 Drawing Figures BACKGROUND OF THE INVENTION AND PRIOR ART The present invention is particularly useful in conjunction with gas producers. The furnace configuration above the grates and ash pit is conventional and includes, for example, stirring means of various types, refractory brick lining, water jacket means, coal introduction means, gas off-take means, and other structure commonly associated with a gas furnace. See, for example, U.S. Pat. No. 2,816,823 to Galusha.

The demand for fuel gases from coal is great, particularly at a time of energy crisis such as is currently being experienced. Coal is available in large amounts, and its utilization in the production of fuel gases is of current interest. Large capacity devices are required to meet needs and, therefore, furnaces of greatly expanded sizes are contemplated. Increase in the physical dimensions, particularly the diameter, however, introduces problems in combustion and ash control not otherwise encountered or of sufficient magnitude to require special attention.

One system of improving combustion heretofore has utilized a rotary grate (U.S. Pat. No. 2,952,357). The present invention subdivides the cross section of the furnace into zones, each yielding ash and depositing the ash onto a series of stationary plates. The ash collected on the plates is removed by ash removal means individually operable relative to each plate. Since the rate of ash removal affects combustion in the particular zone, control over the combustion within the furnace can now be maintained through means for varying the rates of ash removal in the respective zones. These means are responsive to a combustion condition, e.g. temperature.

BRIEF STATEMENT OF THE INVENTION Briefly stated, the present invention is in a gas producing apparatus including in combination means for transversely subdividing a shaft type furnace into a plurality of zones adjacent the ash pit, separate means for removing ash from each of said zones, and means for controlling the rate of ash removal from each of said zones.

More specifically, the present invention is in an ash removal assembly for a gas producer apparatus which is characterized by an ash pit assembly including an ash pit section, a plurality of concentrically disposed tubular members having their distal extremities extending into the lower portion of said burden, and their proximal extremities being in axially stepped relation, the innermost tubular member being the longer, means'coacting between the pit section and the proximal extremities of each of the tubular members for supporting the tubular members in the concentric, axially stepped relation. Axially stepped concentric ash supporting ledges are provided carried by the support means and underlying the spaces created by the tubular members with respect to the furnace wall, each other, and the circular space defined by the innermost tubular member. Means are also provided for removing ash from the ledges. It has been found that, by individually controlling the rate at which ash is removed from'the respective annular spaces, one is able to control the rate of burning in the combustion zone. Control of burning across the entire diameter of the furnace within a relatively fixed combustion zone is essential to improve the efficiency of operation and combustion in large diameter furnaces.

BRIEF DESCRIPTION OF THE DRAWINGS The invention may be better understood by having reference to the annexed drawings wherein:

FIG. 1 is a cross-sectional view of one embodiment of the present invention showing a typical shaft-type furnace having the ash removal system of the present invention.

FIG. 2 is a cross-sectional view of the apparatus as it appears in the broken plane indicated by the line 2-2 of FIG. 1.

FIG. 3 is a diagrammatic illustration of the location of temperature-sensing means for control of the ash removal apparatus hereof.

DETAILED DESCRIPTION OF THE DRAWINGS Referring now more particularly to FIGS. 1 and 2 of the annexed drawings illustrating one embodiment of the invention, adapted for operation at elevated pressures, e.g. 300 psi., it will be observed that the furnace portion of the apparatus generally indicated by the numeral 10 is of conventional shaft furnace structure and includes an outer steel shell 12, an insulation layer 14, and a refractory brick layer 16. Adjacent the hot zone, there is provided a water jacket 18 as a convenient mode of construction in lieu of refractory material. A gas off-take 20 for exhausting the generated gas, e.g. producer gas, is provided through the end closure generally indicated at 22. Also extending through the end closure 22 are inlet conduits 24 and 26 for the introduction of solid carbonaceous material to be burned, for example coal or coke or bricketted carbonaceous material. Extending centrally into the upper portion of the furnace 10 is a stirring mechanism including a shaft 28 mounted for rotation in a bearing 30 and having at its inner portion stirring arms, e.g. arms 30 and 32, extending radially therefrom and rotatable therewith for agitating the carbonaceous charge. A pressure relief tube and valve assembly 34 is also desirably provided. The foregoing portion of the apparatus forms no part of the present invention and, as indicated above, is shown for environmental purposes. As indicated, the present invention is in the ash removal system coacting with a plurality of zones transversely of the shaft furnace.

Whereas heretofore the diameter of the gas producer furnaces has been fairly well limited to from 6 to 12 feet in diameter, the problems experienced in uneven burning of a carbonaceous burden within the furnace manifest themselves to a higher and intolerable degree when the internal diameter of the apparatus exceeds about 12 feet, for example 25 feet. The burning rate tends to be higher centrally of the burden because of the reduced opportunities for heat transfer away from the combustion zone. However, adjacent the sidewalls of the apparatus, heat transfer occurs more readily and the burning rate and degree of completion tends to be slowed. Also, during the traverse of the burden in a downward way and in spite of the presence of agitation means, such as provided by the stirring rod 28 and the radially extending arms 30 and 32, channels may be formed within the burden through which combustion inducing gases may flow more rapidly than through adjacent portions of the burden, causing local cooling and hence less efficient burning. Also, it has been found that fines are collected in pockets within the burden creating less permeable regions, hence adversely affecting gas flow and coal combustion. In order to reduce the carbonaceous material to an ash and to prevent fusion thereof into unmanageable clinkers, the time of exposure to oxidizing gases must be controlled, and this is best accomplished by controlling the rate of downward flow. Although this principle has been practiced heretofore utilizing the rate of downward movement of the burden to control the degree and efficiency of combustion, it has never been done by controlling separate zones within the superposed burden in a single furnace.

To the accomplishment of this end, then, there is provided in the illustrative embodiment an ash pit assembly generally indicated at 36 including a closed sidewall 38 and mounted below the furnace portion 10. There are provided a plurality of concentrically disposed zone defining tubular members, for example inner tubular member 40, intermediate tubular member 42, and outer tubular member 44. The distal extremities of each of the tubular members 40, 42, and 44 are provided conveniently with a tip, for example tips 46, 48, and 50 which are desirably of triangular crosssection. The tips 46, 48, and 50 extend into the bottom or lower portion of the burden where combustion thereof is complete. As is shown best in FIG. 1, the tubular members 40, 42, and 44 are provided with tapered sidewalls, for example sidewalls 52 and 54, on tubular member 40 which diverge in a downward direction. As indicated, the tubular members 40, 42, and 44 are preferably concentrically arranged and the tapered effect of the sidewalls, such as sidewalls 52 and 54, provide in combination with the adjacent sidewalls 56 and 58, for example, an annular space or zone 60 which expands slightly in a radial direction as one proceeds in an axial direction. This tends to minimize jamming of ash and clinker particles within the annuli, e.g. annulus 60. Tubular members 48 and 50 define an annulus or zone 62, and tubular member 44 in combination with the overlapping portion of the sidewall of jacket 18 defines an annular portion or zone 64. The tubular member 40 being the innermost defines no internal annulus but a tapered cylindrical portion or zone 66.

The proximal extremities 68, 70, and 72 of the tubular members 40, 42, and 44, respectively, are in axially stepped relation, the innermost tubular member 40 being the longest in an axial direction, the intermediate member 42 being of intermediate axial length, and the outer or largest diameter tubular member 44 being of the shortest axial length. In the preferred embodiment, the geometric surface in which the proximal extremities of the tubes 40, 42, and 44 lie is an inverted cone. This is convenient for fabrication purposes although not an essential relationship.

The proximal extremities 68, 70, and 72 of the tubular members 40, 42, and 44 are supported by suitable support means such as radially inwardly'extending supports 74 and 76 for tubular member 40; radially inwardly extending support arms 78 and 80 for intermediate length tubular member 42; and radially inwardly extending support arms 82 and 84 for tubular member 44. The number of such radially inwardly extending support arms for any given tubular member may readily be determined by engineering considerations but usually four such arms or six such arms at each level will suffice. The arms also support concentric annular plates for collection of ash from each zone. Thus, the radially inwardly extending arms 82 and 84 support an annular ash collecting plate 86 which underlies the annular zone 64 defined by the tubular member 44 and the water jacket 18. In like manner, the radially inwardly extending arms 78 and support an ash collecting plate 88 which underlies the zone 62 defined by the tubular members 42 and 44. Still further, the radially inwardly extending arms 74 and 76 support an annular ash collecting plate 90 underlying the zone 60 defined by tubular members 40 and 42. In the absence of any means for continuously removing ash material from under each of the zones 60, 62, and 64 and, as will hereinafter be pointed out, the central portion 66, the apparatus would become a batch apparatus and fail to perform after a certain point until the ash accumulation was manually removed.

To this end, therefore, ash removal means are provided dependent upon relative rotation between the plates and such removal means, e.g. scrapers.

As shown in FIGS. 1 and 2, a preferred form of ash removal means includes a body such as the body 90 in the first ash level formed as an annular ring and supported on a plurality of circumferentially spaced wheels such as wheels 92 and 94 which are supported on and guided by circular rail 96 which is in turn supported on radially inwardly extending support arms, such as support arms 82 and 84. The ring 90 carries on its outer surface a ring gear 98 which is adapted to be driven by pinion 100 driven by a motor 102 through a reduction box 104. At circumferentially spaced intervals, the housing 90 also carries scraper blades 106 and 108. While such blades are shown in FIG. 2 to be disposed at 90 intervals whereby four such scrapers are provided for each level, the number of such scrapers is not critical and may be any convenient number. The scrapers such as scrapers 106 and 108 extend radially inwardly and, as best shown in FIG. 2, are desirably configured with a curved inner edge to aid in urging the ash radially outwardly for cascading over the outermost edge of the ash collecting plate, e.g. plate 86, and downwardly by gravity into the ash cone, e.g. ash cone 110. The ash cone receiving and discharging mechanism again forms no part of-the'present invention and may be of any suitable conventional'structure for gas producing apparatus.

In like manner,the second level or intermediate level ash zone in FIG. 1 includes separately operable ash removing means of similar construction to that shown for the first level. Thus, there is provided a housing ring, wheels such as wheel 114, a ring gear such as ring gear 116, a separate circular rail 118, and radially inwardly projecting scraper arms such as scraper arm 120. The scraper arm agains coacts with the ash receiving plate 88 and removes ash generated in the intermediate zone 62. In the same manner as provided for the first ash removal level, independent driving means generally indicated at 122 are also provided for driving the housing 112 carrying the ring gear 116 and the scrapers such as scraper 120 in a rotatory manner to urge ash collected on the annular plate 88 toward the outer edge thereof for cascading into the ash cone 110. Also in like manner, a similar structure for supporting and rotating scraper arms 124 for coaction with ash receiving annular plate 90 is provided. Separate drive means generally indicated at 126 are also provided for driving the ash removal assembly of the third layer. The motor and drive mechanism in the second and third levels is essentially the same as that described for the first level.

The innermost core or zone 66 deposits the ash generated in this region upon a fixed plate 128 carried by suitable framework 130 within the ash pit assembly 36. Instead of an annular scraper, a transaxially movable plow 132 is provided for reciprocation to and fro across the surface of the ash collecting plate 128 to urge ash so collected off the edge, for example edge 134 for cascading into the ash cone 110. The plow 132 is mounted on an arm 136 supported on a roller 138 which is in turn mounted on the frame 130. The outer extremitiy of the arm 136 includes a rack 140 which is mounted for coaction with a pinion 142 and driven by motor 144 through a reducer 146 in similar manner to the aforesaid driving means. Driving means 103, 122, 126, and 145 are independently controllable so that the rate with which each ash removal means at each of the four levels is driven may be made responsive to conditions within the furnace 10.

In the apparatus shown, conditions at the bottom of the burden are sensed for providing the signal to which the individual drive means 103, 122, 126, and 145 are responsive. Since temperature is a convenient parameter for sensing, a support 148 is provided for supporting temperature sensing means such as thermocouples 150, 152, 154, 156, 158, 160, and 162 across a diameter of the furnace 10.

FIG. 3 shows in diagrammatic form the tubular member 18, 50, 48, and 46, and the location of temperature sensing means 150, 152, 154, 156, 158, 160, and 162. For better control, a corresponding set of temperature sensing means 164, 166, 168, 170, 172, and 174 are provided along a 90 related diameter, For convenience, temperature may be recorded according to the following sequence, the numbers in the following table referring to the numbers appearing on the drawing:

By correlating the temperature sensed in accordance with the foregoing recording sequence, the rate at which the individually operable drive means 103, 122, 126, and 145 are operated may beset according to a predetermined value. Thus, if the temperature-sensed in the first zone 64 is too low, the rate at which the drive 103 is operated is decreased so that the temperature has an opportunity to be elevated to the desired combustion temperature.

Air for combustion is introduced through a blast inlet 176. The nature of the oxidizing gas is conventional and its traverse through the furnace is also conventional. Steam or water vapor may be introduced as is well known. There has been provided an apparatus and method for exercising control of burning in especially large diameter furnaces and involving the sensing of a condition obtaining within the furnace to drive individually operable ash removal means and thus control the rate of burning in given zones so as to maintain the hot high temperature combustion zone at a relatively uniform location axially of the furnace. Although the apparatus described herein is especially adapted for use under elevated pressures, e.g. from superatmospheric to as high as 2,000 psi or more, the principles of this invention are applicable as well to operation at lower pressures, e.g. atmospheric pressure. The apparatus hereof while illustrated in conjunction with gas producer apparatus is useful as well in other types of shaft furnaces in which a charge is oxidized or otherwise reacted with a gas.

What is claimed is:

1. A furnace apparatus comprising in combination:

a. a shaft furnace body having a central axis;

b. means for transversely subdividing said furnace into a plurality of zones adjacent the lower end thereof including a plurality of concentrically disposed tubular members having as their common axis the central axis of the shaft furnace;

0. each of said tubular members having adjacent its lower end a horizontal plate for collection of ash from the corresponding zone, said horizontal plates being in axially stepped relation, the plate for the innermost zone being at the lowest step;

d. separate means for removing ash from each of said plates;

e. means in each tubular member for sensing temperature;

f. and separate means responsive to said temperature sensing means for independently controlling the rate of ash removal from each of said zones, respectively.

2. A furnace apparatus in accordance with claim 1 wherein the separate ash removal means includes scraper means coacting with said horizontal plates for removing ash therefrom, and means for causing relative rotation between said plates and said scraper means.

3. A furnace apparatus in accordance with claim 1 wherein the ash removal rate control means includes individual drive means responsive thereto for driving said ash removal means.

4. In a-gas producer apparatus including a large diameter vertically axised shaft furnace, means for introducing particulate carbonaceous material, means for maintaining combustion of the carbonaceous material in a downwardly moving burden, means for introducing an oxidizing gas; means for removing fuel gas from said furnace, and means for removing ash from the base of said furnace, the improvement which comprises in combination:

a. an ash pit assembly including a pit housing at the lower end of said shaft furnace;

b. a plurality of concentrically disposed tubular members having their distal extremities extending into the lower portion of said burden, and the proximal extremities being in axially stepped relation, the innermost tubular member being the longer, and extending into said pit housing, and having as their common axis the vertical axis of said shaft furnace, said concentrically disposed tubular members defining separate zones;

c. means coacting between the pit housing and the proximal extremities of each of said tubular members for supporting said tubular members in said concentric axially stepped relation;

(1. axially stepped concentric ash supporting ledges carried by said support means and underlying the space between adjacent tubular members and a lower ash supporting platform underlying the central tube;

adjacent the distal extremities of said tubular members.

6. An apparatus in accordance with claim 5 wherein individual temperature sensing means are located between adjacent tubular members, between the outermost tubular member and the furnace wall, and centrally of the innermost tubular member. 

1. A FURNACE APPARATUS COMPRISING IN COMBINATION: A. A SHAFT FURNACE BODY HAVING A CENTRAL AXIS; B. MEANS FOR TRANSVERSLY SUBDIVIDING SAID FURNACE INTO A PLURALITY OF ZONES ADJACENT THE LOWER END THEREOF INCLUDING A PLURALITY OF CONCENTRICALLY DISPOSED TUBULAR MEMBERS HAVING AS THEIR COMMON AXIS THE CENTRAL AXIS OF THE SHAFT FURNACE; C. EACH OF SAID TUBULAR MEMBERS HAVING ADJACENT ITS LOWER END A HORIZONTAL PLATE FOR COLLECTION OF ASH FROM THE CORRESPONDING ZONE, SAID HORIZONTAL PLATES BEING IN AXIALLY
 2. A furnace apparatus in accordance with claim 1 wherein the separate ash removal means includes scraper means coacting with said horizontal plates for removing ash therefrom, and means for causing relative rotation between said plates and said scraper means.
 3. A furnace apparatus in accordance with claim 1 wherein the ash removal rate control means includes individual drive means responsive thereto for driving said ash removal means.
 4. In a gas producer apparatus including a large diameter vertically axised shaft furnace, means for introducing particulate carbonaceous material, means for maintaining combustion of the carbonaceous material in a downwardly moving burden, means for introducing an oxidizing gas; means for removing fuel gas from said furnace, and means for removing ash from the base of said furnace, the improvement which comprises in combination: a. an ash pit assembly including a pit housing at the lower end of said shaft furnace; b. a plurality of concentrically disposed tubular members having their distal extremities extending into the lower portion of said burden, and the proximal extremities being in axially stepped relation, the innermost tubular member being the longer, and extending into said pit housing, and having as their common axis the vertical axis of said shaft furnace, said concentrically disposed tubular members defining separate zones; c. means coacting between the pit housing and the proximal extremities of each of said tubular members for supporting said tubular members in said concentric axially stepped relation; d. axially stepped concentric ash supporting ledges carried by said support means and underlying the space between adjacent tubular members and a lower ash supporting platform underlying the central tube; e. means in each separate zone for sensing temperature; and f. separate means responsive to temperature in each of the zones defined by said concentric tubular members for independently removing ash from said ledges and platform, respectively.
 5. An apparatus in accordance with claim 4 including temperature sensing means for sensing ash temperature adjacent the distal extremities of said tubular members.
 6. An apparatus in accordance with claim 5 wherein individual temperature sensing means are located between adjacent tubular members, between the outermost tubular member and the furnace wall, and centrally of the innermost tubular member. 